The present invention relates generally to tieback assemblies and, more particularly, to hybrid-tieback seal assemblies and associated methods of setting such assemblies.
Hydrocarbons, such as oil and gas, are commonly obtained from subterranean formations. The development of subterranean operations and the processes involved in removing hydrocarbons from a subterranean formation are complex. Typically, subterranean operations involve a number of different steps such as, for example, drilling a wellbore at a desired well site, treating the wellbore to optimize production of hydrocarbons, and performing the necessary steps to produce and process the hydrocarbons from the subterranean formation. Controlling the operation of downhole equipment that may be used at each step is an important aspect of performing subterranean operations.
Downhole equipment includes any equipment used downhole to perform subterranean operations. For instance, downhole equipment may include, but is not limited to, equipment used to set wellheads, liner hangers, completion equipment, and/or intervention equipment.
In some instances, mechanical manipulation may be used to control operation of the downhole equipment. Specifically, a setting tool may be lowered into the wellbore on a work string to manipulate downhole equipment to set the device. Alternatively, the setting tool may be lowered downhole on the work string as part of a downhole tool and may be retained therein or retrieved. The term “set(ting)” a device as used herein refers to manipulating a device so that it goes from a first mode of operation to a second mode of operation. Traditional methods of mechanical manipulation of downhole equipment consume precious rig time rendering them undesirable.
In certain other instances, setting pistons (or hydraulic pistons) may be used to set downhole equipment. Specifically, setting pistons may be provided downhole independently (e.g., a setting tool) or as part of downhole equipment (e.g., internal pistons in a hydraulically set packer). However, typically the hydraulic pistons are source referenced in that pressure can be applied to and relieved from the same location in the system. Specifically, the system is typically pressure balanced at the time pressure is applied to the system. This pressure balance prohibits the ability to build a pressure differential and displace volumes, limiting the system's ability to set downhole equipment.
It is therefore desirable to develop methods and systems to more efficiently manipulate downhole equipment.
Current methods used to tie a well back to the surface or subsea wellhead from an existing downhole liner hanger entail running a tieback string into the well. These tieback strings typically have seals at their bottom end that stab into a tieback receptacle or polished bore receptacle of a previously installed downhole system. This typical approach may be problematic in applications where the existing tieback receptacle of the system has limited pressure rating. When performing typical tieback methods with similar systems, there is a risk of pressure induced failure (i.e., bursting or collapsing) in the tieback receptacle and/or the tieback string. As a result, a new and improved method of tying a well back to the surface or subsea wellhead is desirable.
Moreover, a tubing plug or similar device is typically used to hydraulically set various components downhole, including but not limited to hold down and hold up tubular bodies and/or packer seals. The setting typically occurs when the system is pressured up by applying hydraulic pressure by way of hydraulic ports in the system. Once the components are set, the plugging device may be removed by means of drilling, which requires an intervention run to remove any downhole impediments. Hydraulic ports are required for the application of hydraulic pressure to set various downhole components. These hydraulic ports do not allow for tubular metal integrity of the tieback string.
Typically, hydraulic pressure that is applied to the current system elastically deforms the tubulars that the components must set against. Once the pressure is removed, the tubulars relax and a proportion of the setting load may be lost in the components, which may compromise the quality of the component set. Moreover, once the plugging device is removed, the current system cannot be re-pressurized to apply an additional setting load until a second plugging device (e.g., production hanger) has been installed.
It is therefore desirable to develop an improved system of tying a well back to the surface or subsea wellhead that does not utilize a tubing plug or similar device.
While embodiments of this disclosure have been depicted and described and are defined by reference to exemplary embodiments of the disclosure, such references do not imply a limitation on the disclosure, and no such limitation is to be inferred. The subject matter disclosed is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those skilled in the pertinent art and having the benefit of this disclosure. The depicted and described embodiments of this disclosure are examples only, and not exhaustive of the scope of the disclosure.